Biological, mechanical and chemical litter effects on establishment of plant communities

ALEJANDRO LOYDI

Hamburgo

Encuentro; Network Meeting of the Alexander von Humboldt Foundation; 2011

Alexander von Humboldt Stiftung

Litter plays an important role in community organization and their effects depend on litter type, litter amount and environmental conditions. Generally, the effects of litter in forest ecosystems are negative, while in grasslands ranges from strongly negative to slightly positive, depending on the presence of competition and litter origin. In recent years many papers have been published that deal with this subject, but still there is little available information about the role of competition in seedling establishment in grassland ecosystems, and its interaction with litter amounts and litter types. Also, the mechanisms behind this ecologically relevant differential litter effects are not yet fully understood. This research project proposes two experiments and one meta-analysis. The first experiment will test the effects of litter types and amounts, and its interaction with competition, on the emergence of seedling from grasslands and woodlands. The second is a greenhouse experiment that will test mechanical and chemicals effects of litter on vegetation from woodland and grasslands. Finally, a meta-analysis will be made, to combine information of litter effects from grassland ecosystems worldwide; expecting to synthesize the information generated in recent years to seek for general patterns in the response of vegetation to litter in grasslands. In Argentina the Pampas Grasslands are one of the most endangered ecosystems. These areas are threatened by the development of agriculture and animal husbandry, and also by the advance of introduced plant species (e.g Pinus spp.,